The present invention relates to sealing devices in general, and more particularly to improvements in sealing devices which can be used to interrupt communication between two chambers or spaces which are (or are likely to be) maintained at different pressures and are connected to each other by way of a gap. For example, the improved sealing device can be used in ionography imaging chambers wherein sheets of dielectric material must be introduced into and withdrawn from an interelectrode clearance wherein the pressure is normally in the range of 6-20 atmospheres superatmospheric pressure while the sheet is exposed to object-modulated X-rays.
In presently known sealing devices which are used for the aforementioned and similar purposes, the flow of a gaseous or other fluid between chambers or spaces containing fluids which are maintained at different pressures is prevented or interrupted by an inflatable hose or the like or by a deformable solid seal of elastomeric material. As a rule, the sealing element is inserted into a groove at one side of the gap and is deformed, either by admission of pressurized fluid into its interior or because it undergoes deformation during insertion. In the latter instance, the sealing action is more or less permanent which eliminates such seals from use in gaps which must be sealed only from time to time. Inflatable hoses exhibit the drawback that the extent of sealing engagement between their outer sides and the surface at the other side of the gap varies in response to changes in pressure of admitted fluid and also that they are unlikely to collapse and be retracted from the gap except when the pressure therein is reduced below the pressure acting against their external surfaces. Moreover, such inflatable hoses will seal only as long as the pressure therein exceeds the pressure in the gap.